HIGH VOLTAGE NON PUNCH THROUGH IGBT FOR SWITCH MODE POWER SUPPLIES

摘要

A process for forming an NPT IGBT in a thin N type silicon wafer in which the bottom surface of a thin silicon wafer (100 microns thick or less) has a shallow reduced lifetime region in its bottom formed by a light species atom implant to a depth of less than about 2.5 microns. A P+ transparent collector region about 0.5 microns deep is formed in the bottom of the damaged region by a boron implant. A collector contact of A1/Ti/NiV and Ag is sputtered onto the collector region and is annealed at 200°C to 400°C for 30 to 60 minutes. A pre-anneal step before applying the collector metal can be carried out in vacuum at 300°C to 400°C for 30 to 60 seconds.